Targeting apoptosis to overcome cisplatin resistance: a translational study in head and neck cancer.

Purpose: Cisplatin resistance remains a barrier to organ-sparing and survival of patients with advanced head and neck squamous cell carcinoma (HNSCC). Targeted therapies to overcome cisplatin-resistant HNSCC are being developed. Methods and Materials: Cisplatin-sensitive parental HNSCC cell lines and cisplatin-resistant progeny were studied. Pretreatment HNSCC biopsies were used to construct tissue microarrays which were stained for p53 and Bcl-xL. Results: HNSCC cell lines selected for cisplatin resistance had wild-type p53 and high levels of Bcl-xL. Expression of wild-type p53 in cell lines with low Bcl-xL enhanced cisplatin sensitivity. Expression of both Bcl-xL and wild-type p53 caused tumor cells to become cisplatin resistant. Patients whose tumors expressed low levels of p53 and Bcl-xL enjoyed the best organ preservation and disease-free survival whereas patients whose tumors expressed low levels of p53 and high levels of Bcl-xL had the worst outcome. Novel agents that inhibit Bcl-xL or activate p53 function may target cisplatin-resistant HNSCC. Conclusion: Cisplatin resistance in HNSCC is mediated, at least in part, by high Bcl-xL and functional p53.